| 摘要 |
PURPOSE:To exactly detect the presence or absence of a recording signal without necessitating a complicated and highly accurate circuit by using a special comparison reference at the time of executing said detection even track of a magnetic disk such as a floppy disk, etc. CONSTITUTION:A reproduced signal from a floppy disk 11 is supplied to a DC implementation circuit 15 through a reproducing amplifier 13 and an AC amplifier 14. An output from the circuit 15 is inputted to an A/D converter 18. The converter 18 converts the output from the circuit 15 into a digital value by using a reference voltage from a reference power supply circuit 19. The resulting conversion output is taken in by a system controller 20 to decide on the presence or absence of a recorded signal. For this operation, the controller 20 uses a reproduced output from a part of the disk 11 other than the disk's signal-recorded track extent or that at a time when the disk 11 is stationary as a comparison reference. In such a way, the detection can be executed exactly without a need for making the circuitry complicated and highly accurate.
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